WO2020142921A1 - Optical detection module and distance measuring device - Google Patents

Abstract

An optical detection module and a distance measuring device, the optical detection module (600) comprising: a photoelectric conversion circuit (610) used for converting an optical pulse signal reflected back by an object into an electrical pulse signal; N digitizing modules (620), which are connected in series or connected in parallel to the photoelectric conversion circuit (610), and which is used for separately converting the electrical pulse signal into N digitized signals, wherein N≥2, an nth digitizing module (620) comprises an nth stage amplifying circuit and an nth stage digitizing circuit, an output end of the nth stage amplifying circuit is connected to an input end of the nth stage digitizing circuit, and n=1, 2...N; and an operation circuit (630) used for determining the distance between the object and the optical detection module (600) according to the N digitized signals. The present optical detection module and distance measuring device solve the problem in which it is difficult to determine the time position of a target pulse when the measurement target distance is close, and a measurement blind area is thus generated, and achieve the accurate detection of the flight time of an optical pulse sequence.

Description

Optical detection module and distance measuring device Technical field

The invention relates to the technical field of circuits, in particular to an optical detection module and a distance measuring device.

Background technique

Laser ranging is a perception system for the outside world, which can obtain the spatial distance information in the direction of emission. The principle is to actively emit a laser pulse signal to the outside, detect the reflected pulse signal, and judge the distance of the measured object according to the time difference between transmission and reception. The same optical path laser ranging system will inevitably encounter the 0-level reflection problem, that is, after the laser pulse is generated, it will be reflected before flying out of the ranging device. This reflection may be caused by the lens, prism, inner wall, etc. If the target is measured at this time If the distance is close, the front part of the target reflection pulse overlaps with the back part of the zeroth-order reflection pulse to form a continuous pulse. It is difficult to determine the time position of the target pulse, resulting in a measurement dead zone.

Summary of the invention

The light detection module and the distance measuring device provided by the embodiments of the present invention solve the problem that it is difficult to determine the time position of the target pulse when the measurement target distance is close, and a measurement blind zone is generated.

In a first aspect, the present invention provides a light detection module. The light detection device includes:

The photoelectric conversion circuit is used to convert the optical pulse signal reflected by the object into an electrical pulse signal;

N digitizing modules, the N digitizing modules are connected in series or in parallel to the photoelectric conversion circuit for converting the electrical pulse signal into N digitizing signals, N ≥ 2; wherein, the nth digitizing module includes An nth stage amplifying circuit and an nth stage digitizing circuit, the output end of the nth stage amplifying circuit is connected to the input end of the nth stage digitizing circuit, n=1, 2...N;

An arithmetic circuit is used to determine the distance between the object and the light detection device according to the n digitized signals.

On the other hand, the present invention provides a distance measuring device, including:

Transmitting module, used to transmit optical pulse sequence;

A scanning module, used to sequentially change the propagation path of the optical pulse sequence emitted by the transmitting module to different directions to exit;

As in the above-mentioned light detection module, at least part of the light signal reflected by the light pulse sequence through the object is incident on the photoelectric conversion circuit in the light detection device after passing through the scanning module, and the photoelectric conversion circuit is used to The at least part of the optical signal is converted into an electrical pulse signal.

The embodiment of the present invention solves the problem that it is difficult to determine the time position of the target pulse due to the close measurement of the target distance and the measurement blind area by grading, amplifying and digitizing the detected light pulse sequence reflected by the object, thereby realizing the accuracy of the optical pulse sequence flight time Detection.

BRIEF DESCRIPTION

In order to more clearly explain the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, without paying any creative work, other drawings can be obtained based on these drawings.

1 is an example of a wiring diagram of an anti-saturation amplifier circuit according to an embodiment of the present invention;

2 is an example of the clamping effect of the current bypass circuit of the embodiment of the present invention;

3 is an example of a wiring diagram of an amplifier bypass circuit according to an embodiment of the invention;

4 is an example of the clamping effect of the amplifier bypass circuit of the embodiment of the present invention;

Fig. 5 is an example where the pulses reflected by the 0th order reflection and the target object overlap;

6 is a schematic block diagram of an optical detection module according to an embodiment of the present invention;

7 is an example of serialization of digital modules according to an embodiment of the present invention;

8 is an example of the output signal of the first level digitization module of the embodiment of the present invention;

9 is a schematic block diagram of a distance measuring device according to an embodiment of the present invention;

10 is a schematic diagram of an embodiment of the distance measuring device of the present invention using a coaxial optical path.

detailed description

The technical solutions in the embodiments of the present invention will be described clearly and completely in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative labor fall into the protection scope of the present invention.

In the process of measuring the relative distance of the target by measuring the round-trip time of the optical pulse sequence, the power of the optical pulse sequence reflected by the target will be violent due to the change in the target distance and reflection characteristics of the measured target in a large dynamic range. Variations, for example, in the vicinity of 0.1m and the distance of 50m, the difference of the reflected signal strength can reach 10 ⁴ -10 ⁵ level; and in order to ensure high-precision distance measurement, it is necessary to make the distance measuring device in a wide dynamic range The optical pulse signal is accurately detected within.

An embodiment of the present invention provides an anti-saturation amplifier circuit, including: an operational amplifier, a first resistor, and an amplifier bypass circuit; wherein, one end of the first resistor receives the electrical pulse signal, and the other of the first resistor One end is connected to the reverse input end of the operational amplifier, the forward input end of the operational amplifier is connected to a reference voltage, and the output end of the operational amplifier outputs the amplified electrical pulse signal; the amplifier bypass circuit is connected to the Between the inverting input and output of the operational amplifier.

Among them, the anti-saturation circuit refers to the use of higher amplification factors for small signals detected in a wide dynamic range signal to ensure accurate measurement of long-distance measurements; for large signals detected, the multiples are quickly reduced to make The overall output amplitude is limited to the normal output range of the system. When the output of the operational amplifier exceeds the output range, it is called the saturation output of the operational amplifier. It takes recovery time to return to the normal working state after the saturation output of the operational amplifier occurs. That is to say, the saturation output of the operational amplifier will make the system unable to respond quickly and continuously, resulting in a system measurement dead zone; and it will cause distortion of the trailing edge measurement and affect the signal measurement. The anti-saturation amplifier circuit provided by the embodiment of the present invention can effectively avoid the saturation problem of the operational amplifier.

Optionally, the amplifier bypass circuit includes a second resistor; or a circuit in which the second resistor and the third resistor are connected in series.

Optionally, the amplifier bypass circuit further includes a first diode; the first diode is connected in parallel with the second resistor or the third resistor.

Optionally, the anti-saturation amplifier circuit includes a current bypass circuit, connected to one end of the first resistor, for limiting the current passing through the first resistor.

Optionally, the current bypass circuit includes a second diode.

Optionally, the anti-saturation amplifier circuit includes a voltage bypass circuit, connected to the output terminal of the operational amplifier, for limiting the output voltage of the anti-saturation amplifier circuit.

Optionally, the voltage bypass circuit includes a fourth resistor and a third diode, one end of the fourth resistor is connected to the output terminal of the operational amplifier, and the other end of the fourth resistor is connected to the The anode of the third diode also serves as the output of the anti-saturation amplifier circuit, and the cathode of the third diode is grounded.

In one embodiment, referring to FIG. 1, FIG. 1 shows an example of a wiring diagram of an anti-saturation amplifier circuit. As shown in FIG. 1, the anti-saturation amplifier circuit 100 includes: an operational amplifier U1, a first resistor R1, an amplifier bypass circuit 110, a current bypass circuit 120, and a voltage bypass circuit 130;

Wherein, one end of the first resistor R1 receives the electrical pulse signal Signal_in, and the other end of the first resistor R1 is connected to the inverting input terminal -IN of the operational amplifier U1;

The positive input terminal +IN of the operational amplifier U1 is connected to the reference voltage AMP_REF, and the output terminal OUT of the operational amplifier U1 outputs the amplified electrical pulse signal Signal_out;

The amplifier bypass circuit 110 is connected between the inverting input terminal -IN and the output terminal OUT of the operational amplifier U1. The amplifier bypass circuit 110 includes a second resistor R2, a third resistor R3 and a diode D2. One end of the third resistor R3 is connected to the inverting input terminal -IN of the operational amplifier U1, and the other end of the third resistor R3 is connected to the second resistor R2 and the diode D2 connected in parallel, that is, the third resistor The other end of R3 is connected to the second resistor R2 and the anode of the diode D2, and the other end of the second resistor R2 and the cathode of the diode D2 are connected to the output terminal OUT of the operational amplifier U1;

The current bypass circuit 120 is connected to one end of the first resistor R1. The current bypass circuit 120 includes a diode D1. The anode of the diode D1 is connected to one end of the first resistor R1. The diode D1 Is connected to the reference voltage CLAP_REF;

The voltage bypass circuit 130 is connected to the output terminal OUT of the operational amplifier U1. The voltage bypass circuit 130 includes a fourth resistor R4 and a diode D3. One end of the fourth resistor R4 is connected to the operational amplifier U1. At the output terminal OUT, the other end of the fourth resistor R4 is connected to the anode of the diode D3, the connection point of the other end of the fourth resistor R4 and the anode of the diode D3 outputs an amplified electrical pulse signal Signal_out, and the diode D3 The negative electrode is connected to the reference voltage CLAP_REF_01.

Among them, the current bypass circuit 120 in the anti-saturation amplifier circuit 100 can ensure that the input signal to the operational amplifier is within a small range to prevent the saturation of the operational amplifier; and the voltage bypass circuit 130 adaptively reduces the gain when the signal is large To avoid saturation of the op amp.

As shown in FIG. 1, in the signal link, the diode D1 in the current bypass circuit 120 is turned on when the voltage value of the electrical pulse signal Signal_in in the signal link is higher than the conduction voltage drop of the diode D1, and The greater the exceeded voltage, the greater the on-current, and the voltage of the electrical pulse signal Signal_in can be clamped near the on-voltage of the diode. In the current signal link, the first resistor R1 is located after the diode D1, which is equivalent to converting the current signal into a voltage through the resistor and then clamping. At present, the output signal of the lidar laser sensor is approximately a current signal. When the input current is large, the voltage drop generated by the first resistor R1 increases, and when the conduction voltage drop of the diode D1 is exceeded, the diode D1 is turned on. To the bypass clamp function, that is, when the input current is large, there is a current bypass path in the current signal link, and the larger the current signal, the greater the current through the current bypass path shown, which limits the The maximum electrical current of the first resistor R1 is shown in FIG. 2, which shows an example of the clamping effect of the current bypass circuit according to an embodiment of the present invention, where the solid line is the actual signal, the dotted line is the clamping voltage, and the dotted line It is the signal after clamping.

Optionally, the current bypass circuit 120 may also use a Zener diode or TVS diode; the clamping voltage may be the breakdown voltage of the Zener diode or TVS diode.

The voltage bypass circuit 130 composed of the fourth resistor R4 and the diode D3 is provided with the fourth resistor R4 before the diode D3, that is, a voltage divider circuit composed of the fourth resistor R4 and the diode D3, which can ensure a small signal When the signal does not decay, the signal output to the subsequent stage does not exceed the conduction voltage drop of the diode when the signal is larger than the conduction voltage drop of the diode; this can reduce the input voltage of the post-stage op amp and prevent the output of the post-stage op amp saturation.

The amplifier bypass circuit 110 includes a second resistor R2, a third resistor R3, and a diode D2. When the input signal is small, the voltage difference between the second resistor R2 and the diode D2 is small. At this time, the diode D2 is not turned on, and the diode The resistance of D2 is larger; when the input signal is larger, the voltage difference between the second resistor R2 and the diode D2 increases to exceed the conduction voltage drop of the diode D2, the diode D2 is turned on, and the second resistor R2 and the diode D2 are connected in parallel The equivalent resistance decreases and the magnification decreases. The larger the input signal, the smaller the amplification factor until it is reduced to a minimum amplification factor. That is, when the input signal is a small signal, the amplification factor is the largest. When the input signal gradually increases, the gain of the amplifier circuit gradually decreases to a minimum amplification factor. Optionally, the amplifier bypass circuit 110 can also omit the third resistor R3, because the operational amplifier has different amplification parameters and can be kept stable at a smaller amplification factor, the third resistor R3 can be omitted, As shown in FIG. 3, FIG. 3 shows an example of a wiring diagram of an amplifier bypass circuit of an embodiment of the present invention. When the input signal is small, the diode D2 is not turned on, and the gain of the operational amplifier U1 is determined by the first resistor R1 and the second resistor R2; when the input signal is large, the diode D2 is turned on, and the second resistor R2 and the diode D2 are connected in parallel The equivalent resistance of is reduced, and the amplification factor is gradually reduced until the output signal is reduced to not exceed the maximum conduction voltage drop of the diode. As shown in FIG. 4, FIG. 4 shows an example of the clamping effect of the amplifier bypass circuit according to an embodiment of the present invention. When the input signal is a small signal on the left, the solid line is the small signal before amplification, and the dotted line is Output signal after amplification When the input signal is a large signal on the right, the solid line is the large signal before amplification, and the dotted line is the output signal after amplification.

After the light pulse sequence reflected by the target object passes through the amplification circuit, some information in the pulse signal may be missing or partially missing, such as pulse energy information. In the same optical path laser ranging, it will inevitably encounter the problem of 0-level reflection. Among them, 0-level reflection refers to the reflection pulse generated after the laser pulse is generated before flying out of the ranging device. This reflection may be caused by the lens, prism, The inner wall is generated; if the measurement target distance is closer at this time, the front of the pulse reflected by the target object and the rear of the zero-order reflected pulse may overlap to form a continuous pulse, which makes the time position of the target pulse difficult to determine. This results in a measurement dead zone. As shown in FIG. 5, FIG. 5 shows an example in which the pulses reflected by the 0th order reflection and the target object overlap.

Based on the above considerations, an embodiment of the present invention provides a light detection module. Referring to FIG. 6, FIG. 6 shows a schematic block diagram of a light detection module according to an embodiment of the present invention. As shown in FIG. 6, the light detection module 600 includes:

The photoelectric conversion circuit 610 is used to convert the optical pulse signal reflected by the object into an electrical pulse signal;

N digitizing modules 620, the N digitizing modules are connected in series or parallel to the photoelectric conversion circuit for converting the electrical pulse signal into N digitized signals, N ≥ 2; wherein, the nth digitizing module It includes an nth stage amplifying circuit and an nth stage digitizing circuit, the output end of the nth stage amplifying circuit is connected to the input end of the nth stage digitizing circuit, n=1, 2, ... N;

The arithmetic circuit 630 is used for determining the distance between the object and the light detection module according to the n digitized signals.

Among them, when the detected 0-level reflected T0 pulse signal and the pulse reflected by the target object are amplified indiscriminately after passing through the amplification circuit, this is not conducive to distinguishing the 0-level reflected T0 pulse signal and the pulse reflected by the target object, so You can make the T0 signal as small as possible after passing through the amplifier circuit, so as not to affect the collection of nearby signals and bring about a blind spot. The hierarchical digitization module amplifies and digitizes the optical pulse signals reflected by different objects to different degrees, which can accurately distinguish the 0-level reflected T0 pulse signal and the pulse reflected by the target object to obtain accurate time information, thereby Improve the measurement accuracy of the light detection module.

Optionally, when the N digitizing modules are connected in series to the photoelectric conversion circuit, the n+1th stage amplifying circuit is used to amplify the output signal of the nth stage amplifying circuit to obtain the n+th stage Level 1 amplified signal;

The n+1th stage digital circuit is connected to the n+1th stage amplification circuit, and is configured to convert the n+1th stage amplification signal into an n+1th stage digital signal.

Optionally, when the N digitizing modules are connected in parallel to the photoelectric conversion circuit, the amplification factors of the N digitizing modules are different.

Optionally, the n-th digitizing circuit includes a time-to-digital converter or an analog-to-digital converter.

Optionally, when the n-th digitizing circuit includes an analog-to-digital converter, the analog-to-digital converter converts the n-th amplified signal to an n-th digitized signal based on a predetermined sampling frequency.

Optionally, when the n-th digitizing circuit includes a time-to-digital converter, the time-to-digital converter includes several different sampling thresholds; wherein, the number of sampling thresholds of the n+1th digitizing circuit is greater than the nth The number of sampling thresholds of the level digitizing circuit.

In some embodiments, the sampling threshold of the n+1th digitizing circuit is greater than the sampling threshold of the nth digitizing circuit.

In one embodiment, referring to FIG. 7, FIG. 7 shows an example of serialization of digital modules in an embodiment of the present invention. As shown in FIG. 7, there are N-level amplification circuits (N≥2) among the N digitization modules, and the signals of each level of the amplification circuit can be digitized. Wherein, the digitalization method includes and is not limited to ADC (Analog to Digital Converter) and TDC (Time to Digital Converter).

The amplification factor of the first-stage amplifier circuit is small. When the output signal of the sensor passes through the first-stage amplifier circuit, the pulse signal output has a smaller amplification factor. At this time, the T0 signal reflected by the 0th stage is not amplified much; When the target object is relatively close, the signal reflected by the near target object is generally relatively large, and a relatively large pulse signal can be obtained without going through a large amplification factor. In other words, the optical signal reflected back is relatively strong, and although it is amplified by a smaller magnification, it is still sufficient for digital circuit acquisition. Then, at the output of the first-stage amplifier circuit, the T0 signal is smaller than the signal reflected by the nearby target object, and there is sufficient discrimination to facilitate the digital circuit acquisition. Taking the TDC acquisition method as an example, in the output signal of the first-stage amplification circuit, the leading edge of the near-zone blind zone signal is less affected by T0, and it can be better collected by the TDC method, as shown in FIG. 8, which shows this An example of the output signal of the first-level digitization module of the embodiment of the invention. When TDC sampling is used, the number of sampling thresholds is 4, and the sampling thresholds are Vf01, Vf02, Vf03, and Vf04, and Vf01<Vf02<Vf03<Vf04, because At the output of the first-stage amplifier circuit, the signal reflected by the near target object is sufficiently distinguished from the T0 signal, so it is easy to sample the signal reflected by the near target object by different sampling thresholds, without being affected by the T0 signal. The effect avoids the problem of measurement blind zone, which is beneficial to improve the accuracy of measurement.

When the output signal of the nth stage amplifier circuit is input to the n+1th stage amplifier circuit, the signal reflected by the target object is further amplified. When the target object is farther, the signal strength reflected by the farther target object is weaker. Enlarge with a larger magnification factor in order to obtain the corresponding time information. It can be seen from this that the output signal of the Nth-stage amplifier circuit is the signal after multi-stage amplification from the first-stage amplifier circuit to the Nth-stage amplifier circuit. It should be noted that when the digitizing modules are connected in series, the amplification factors of the N amplification circuits in the first-stage to N-th stages of amplification circuits may be the same or different, which is not limited herein.

Therefore, according to the intensity of the received optical pulse signal, the output results of different digital modules can be used to further improve the measurement accuracy of the optical detection module.

Optionally, the arithmetic circuit determines the weights of the N digitized signals according to a predetermined strategy, and obtains the reception time of the received optical pulse signal based on the N digitized signals and the corresponding weights.

Optionally, the predetermined strategy includes: determining the weight of the n-th digitizing circuit according to the intensity of the received optical pulse signal. Among them, the digitized information of the output signal of the first-stage amplifier circuit is used when the optical pulse signal is relatively strong in the vicinity; the digitized information of the output signal of the second-stage or N-stage amplifier circuit is used when the distance is longer and the optical pulse signal is smaller information. The test data required by the actual situation and design needs can also be different, and the results of different stages of digitization modules can be used as the data basis for calculating the reception time of the received optical pulse signal. It should be noted that the results of one level of digitization module among the N digitized signals can be used, or the results obtained by synthesizing multiple digitized results and corresponding weights can be used for analysis and calculation to obtain the received optical pulse signal. time.

In addition, in the prior art, after a sufficiently large amplifying circuit, the pulse amplitude information of the larger optical pulse signal has been "cut off", and the related energy information is also drowned out. The detection module of the embodiment of the present invention can also collect pulse energy information more accurately through hierarchical amplification and digitization.

It should be noted that, in the light detection module of the embodiment of the present invention, the anti-saturation amplifier circuit of the embodiment of the present invention may be used, or other forms of amplifier circuits may be used, which is not limited herein.

An embodiment of the present invention also provides a distance measuring device, including:

Transmitting module, used to transmit optical pulse sequence;

A scanning module, used to sequentially change the propagation path of the optical pulse sequence emitted by the transmitting module to different directions to exit;

In the light detection module as described above, at least part of the light signal reflected back from the object by the light pulse sequence is incident on the photoelectric conversion circuit in the light detection device after passing through the scanning module, and the photoelectric conversion circuit is used to The at least part of the optical signal is converted into an electrical pulse signal.

Optionally, the scanning module includes a moving optical element for changing the propagation direction of the light pulse sequence from the distance measuring module before exiting.

Optionally, the optical element includes a first light refracting element and a second light refracting element disposed oppositely, and the first light refracting element and the second light refracting element each include a pair of opposite non-parallel surfaces ;

The scanning module further includes a driving module for driving the first light refractive element and the second light refractive element to rotate at different speeds and/or directions.

Optionally, the optical element further includes a third light refraction element arranged in parallel with the first light refraction element and the second light refraction element. The third light refraction element includes non-parallel To the surface

The driving module is also used to drive the third light refracting element to rotate around a rotation axis.

The light detection modules provided by the various embodiments of the present invention may be applied to a distance measuring device, and the distance measuring device may be an electronic device such as a laser radar or a laser distance measuring device. In one embodiment, the distance measuring device is used to sense external environment information, for example, distance information, azimuth information, reflection intensity information, speed information, etc. of the environmental target. In an implementation manner, the distance measuring device can detect the distance between the detecting object and the distance measuring device by measuring the time of light propagation between the distance measuring device and the detection object, that is, Time-of-Flight (TOF). Alternatively, the distance measuring device may also detect the distance between the detected object and the distance measuring device through other techniques, such as a distance measuring method based on phase shift measurement, or a distance measuring method based on frequency shift measurement. There are no restrictions.

For ease of understanding, the following describes the working process of distance measurement in conjunction with the distance measurement device 900 shown in FIG. 9.

As shown in FIG. 9, the distance measuring device 900 may include a transmitting circuit 910, a receiving circuit 920, a sampling circuit 930 and an arithmetic circuit 940.

The transmission circuit 910 may transmit a sequence of light pulses (for example, a sequence of laser pulses). The receiving circuit 920 can receive the optical pulse sequence reflected by the detected object, and photoelectrically convert the optical pulse sequence to obtain an electrical signal, which can be output to the sampling circuit 930 after processing the electrical signal. The sampling circuit 930 can sample the electrical signal to obtain the sampling result. The arithmetic circuit 940 may determine the distance between the distance measuring device 900 and the detected object based on the sampling result of the sampling circuit 930.

Optionally, the distance measuring device 900 may further include a control circuit 950, which can control other circuits, for example, can control the working time of each circuit and/or set parameters for each circuit.

It should be understood that although the distance measuring device shown in FIG. 9 includes a transmitting circuit, a receiving circuit, a sampling circuit, and an arithmetic circuit for emitting a beam of light for detection, the embodiments of the present application are not limited thereto, and the transmitting circuit , The number of any one of the receiving circuit, the sampling circuit, and the arithmetic circuit may also be at least two, for emitting at least two light beams in the same direction or respectively in different directions; wherein, the at least two light paths may be simultaneously The shot may be shot at different times. In one example, the light-emitting chips in the at least two emission circuits are packaged in the same module. For example, each emitting circuit includes a laser emitting chip, and the die in the laser emitting chips in the at least two emitting circuits are packaged together and housed in the same packaging space.

In some implementations, in addition to the circuit shown in FIG. 9, the distance measuring device 900 may further include a scanning module 960 (not shown) for changing at least one laser pulse sequence emitted by the transmitting circuit to change the propagation direction.

Among them, the module including the transmission circuit 910, the reception circuit 920, the sampling circuit 930, and the operation circuit 940, or the module including the transmission circuit 910, the reception circuit 920, the sampling circuit 930, the operation circuit 940, and the control circuit 950 may be called a measurement A distance module, the distance measuring module may be independent of other modules, for example, the scanning module 960.

A coaxial optical path may be used in the distance measuring device, that is, the light beam emitted by the distance measuring device and the reflected light beam share at least part of the optical path in the distance measuring device. For example, after at least one laser pulse sequence emitted by the transmitting circuit is emitted by the scanning module to change the propagation direction, the laser pulse sequence reflected by the detection object passes through the scanning module and enters the receiving circuit. Alternatively, the distance measuring device may also adopt an off-axis optical path, that is, the light beam emitted by the distance measuring device and the reflected light beam are respectively transmitted along different optical paths in the distance measuring device. 10 shows a schematic diagram of an embodiment of the distance measuring device of the present invention using a coaxial optical path.

The distance measuring device 1000 includes a distance measuring module 1010, and the distance measuring module 1010 includes a transmitter 1003 (which may include the above-mentioned transmitting circuit), a collimating element 1004, and a detector 1005 (which may include the above-mentioned receiving circuit, sampling circuit, and arithmetic circuit) and Optical path changing element 1006. The ranging module 1010 is used to emit a light beam, and receive back light, and convert the back light into an electrical signal. Among them, the transmitter 1003 may be used to transmit a sequence of light pulses. In one embodiment, the transmitter 1003 may emit a sequence of laser pulses. Optionally, the laser beam emitted by the transmitter 1003 is a narrow-bandwidth beam with a wavelength outside the visible light range. The collimating element 1004 is disposed on the exit optical path of the emitter, and is used to collimate the light beam emitted from the emitter 1003, and collimate the light beam emitted from the emitter 1003 into parallel light to the scanning module. The collimating element is also used to converge at least a part of the return light reflected by the detection object. The collimating element 1004 may be a collimating lens or other element capable of collimating the light beam.

In the embodiment shown in FIG. 10, the optical path changing element 1006 is used to combine the transmitting optical path and the receiving optical path in the distance measuring device before the collimating element 1004, so that the transmitting optical path and the receiving optical path can share the same collimating element, so that the optical path More compact. In some other implementation manners, the transmitter 1003 and the detector 1005 may use respective collimating elements, and the optical path changing element 1006 is disposed on the optical path behind the collimating element.

In the embodiment shown in FIG. 10, since the beam aperture of the light beam emitted by the transmitter 1003 is small and the beam aperture of the return light received by the distance measuring device is large, the light path changing element can use a small area mirror to The transmitting optical path and the receiving optical path are combined. In some other implementations, the light path changing element may also use a mirror with a through hole, where the through hole is used to transmit the outgoing light of the emitter 1003, and the mirror is used to reflect the return light to the detector 1005. In this way, it is possible to reduce the blocking of the return light by the support of the small mirror in the case of using the small mirror.

In the embodiment shown in FIG. 10, the optical path changing element is offset from the optical axis of the collimating element 1004. In some other implementations, the optical path changing element may also be located on the optical axis of the collimating element 1004.

The distance measuring device 1000 further includes a scanning module 1002. The scanning module 1002 is placed on the exit optical path of the distance measuring module 1010. The scanning module 1002 is used to change the transmission direction of the collimated light beam 1019 emitted through the collimating element 1004 and project it to the external environment, and project the return light to the collimating element 1004. . The returned light is converged on the detector 1005 via the collimating element 1004.

In one embodiment, the scanning module 1002 may include at least one optical element for changing the propagation path of the light beam, wherein the optical element may change the propagation path of the light beam by reflecting, refracting, diffracting, etc. the light beam. For example, the scanning module 1002 includes a lens, a mirror, a prism, a galvanometer, a grating, a liquid crystal, an optical phased array (Optical Phased Array), or any combination of the above optical elements. In one example, at least part of the optical element is moving, for example, the at least part of the optical element is driven to move by a driving module, and the moving optical element can reflect, refract or diffract the light beam to different directions at different times. In some embodiments, multiple optical elements of the scanning module 1002 may rotate or vibrate about a common axis 1009, and each rotating or vibrating optical element is used to continuously change the direction of propagation of the incident light beam. In one embodiment, the multiple optical elements of the scanning module 1002 may rotate at different rotation speeds, or vibrate at different speeds. In another embodiment, at least part of the optical elements of the scanning module 1002 can rotate at substantially the same rotational speed. In some embodiments, the multiple optical elements of the scanning module may also rotate around different axes. In some embodiments, the multiple optical elements of the scanning module may also rotate in the same direction, or rotate in different directions; or vibrate in the same direction, or vibrate in different directions, which is not limited herein.

In one embodiment, the scanning module 1002 includes a first optical element 1014 and a driver 1016 connected to the first optical element 1014. The driver 1016 is used to drive the first optical element 1014 to rotate about a rotation axis 1009 to change the first optical element 1014. The direction of the collimated beam 1019. The first optical element 214 projects the collimated light beam 219 to different directions. In one embodiment, the angle between the direction of the collimated light beam 1019 changed by the first optical element and the rotation axis 1009 changes as the first optical element 1014 rotates. In one embodiment, the first optical element 1014 includes a pair of opposed non-parallel surfaces through which the collimated light beam 1019 passes. In one embodiment, the first optical element 1014 includes a prism whose thickness varies along at least one radial direction. In one embodiment, the first optical element 1014 includes a wedge-angle prism, which aligns the straight beam 1019 for refraction.

In one embodiment, the scanning module 1002 further includes a second optical element 1015. The second optical element 1015 rotates around a rotation axis 1009. The rotation speed of the second optical element 1015 is different from the rotation speed of the first optical element 1014. The second optical element 1015 is used to change the direction of the light beam projected by the first optical element 1014. In one embodiment, the second optical element 1015 is connected to another driver 1017, and the driver 1017 drives the second optical element 1015 to rotate. The first optical element 1014 and the second optical element 1015 may be driven by the same or different drivers, so that the rotation speed and/or rotation of the first optical element 214 and the second optical element 215 are different, thereby projecting the collimated light beam 1019 to the outside space Different directions can scan a larger spatial range. In one embodiment, the controller 1018 controls the drivers 1016 and 1017 to drive the first optical element 1014 and the second optical element 1015, respectively. The rotation speeds of the first optical element 1014 and the second optical element 1015 may be determined according to the area and pattern expected to be scanned in practical applications. Drives 1016 and 1017 may include motors or other drives.

In one embodiment, the second optical element 1015 includes a pair of opposed non-parallel surfaces through which the light beam passes. In one embodiment, the second optical element 1015 includes a prism whose thickness varies along at least one radial direction. In one embodiment, the second optical element 1015 includes a wedge angle prism.

In one embodiment, the scanning module 1002 further includes a third optical element (not shown) and a driver for driving the third optical element to move. Optionally, the third optical element includes a pair of opposed non-parallel surfaces through which the light beam passes. In one embodiment, the third optical element includes a prism whose thickness varies along at least one radial direction. In one embodiment, the third optical element includes a wedge angle prism. At least two of the first, second and third optical elements rotate at different rotational speeds and/or turns.

The rotation of each optical element in the scanning module 1002 can project light into different directions, for example, the directions of the light 1011 and 1013, so that the space around the distance measuring device 1000 is scanned. When the light 1011 projected by the scanning module 1002 hits the object 1001 to be detected, a part of the light object 1001 is reflected to the distance measuring device 1000 in a direction opposite to the projected light 1011. The returned light 1012 reflected by the detected object 1001 passes through the scanning module 1002 and enters the collimating element 1004.

The detector 1005 and the transmitter 1003 are placed on the same side of the collimating element 1004. The detector 1005 is used to convert at least part of the returned light passing through the collimating element 1004 into an electrical signal.

In one embodiment, each optical element is coated with an antireflection coating. Optionally, the thickness of the antireflection film is equal to or close to the wavelength of the light beam emitted by the emitter 103, which can increase the intensity of the transmitted light beam.

In one embodiment, a filter layer is plated on the surface of an element on the beam propagation path in the distance measuring device, or a filter is provided on the beam propagation path to transmit at least the wavelength band of the beam emitted by the transmitter, Reflect other bands to reduce the noise caused by ambient light to the receiver.

In some embodiments, the transmitter 1003 may include a laser diode through which laser pulses in the order of nanoseconds are emitted. Further, the laser pulse receiving time may be determined, for example, by detecting the rising edge time and/or the falling edge time of the electrical signal pulse. In this way, the distance measuring device 1000 can use the pulse reception time information and the pulse emission time information to calculate the TOF, thereby determining the distance between the detected object 1001 and the distance measuring device 1000.

The distance and orientation detected by the distance measuring device 1000 can be used for remote sensing, obstacle avoidance, mapping, modeling, navigation, and the like. In one embodiment, the distance measuring device of the embodiment of the present invention can be applied to a mobile platform, and the distance measuring device can be installed on the platform body of the mobile platform. A mobile platform with a distance measuring device can measure the external environment, for example, measuring the distance between the mobile platform and obstacles for obstacle avoidance and other purposes, and performing two-dimensional or three-dimensional mapping on the external environment. In some embodiments, the mobile platform includes at least one of an unmanned aerial vehicle, a car, a remote control car, a robot, and a camera. When the distance measuring device is applied to an unmanned aerial vehicle, the platform body is the fuselage of the unmanned aerial vehicle. When the distance measuring device is applied to an automobile, the platform body is the body of the automobile. The car may be a self-driving car or a semi-automatic car, and no restriction is made here. When the distance measuring device is applied to a remote control car, the platform body is the body of the remote control car. When the distance measuring device is applied to a robot, the platform body is a robot. When the distance measuring device is applied to a camera, the platform body is the camera itself.

The present invention provides a laser emission solution that meets human eye safety regulations by providing the above-mentioned light emitting device, distance measuring device and mobile platform. When a single failure occurs in the system, the circuit in the above device can ensure that the laser radiation value does not exceed the safety Standard value, so as to ensure the safety of the laser device.

The technical terms used in the embodiments of the present invention are only used to describe specific embodiments and are not intended to limit the present invention. In this text, the singular forms "a", "the", and "said" are used to include plural forms unless the context clearly dictates otherwise. Further, the use of "including" and/or "comprising" in the specification refers to the existence of the described features, wholes, steps, operations, elements, and/or components, but does not exclude the presence or addition of one or more Other features, wholes, steps, operations, elements and/or components.

The corresponding structures, materials, actions, and equivalents of all devices or steps and functional elements (if any) in the appended claims are intended to include any structures, materials, or actions for performing the function in combination with other specifically required elements. The description of the present invention is given for the purpose of embodiments and description, but is not intended to be exhaustive or to limit the invention to the disclosed form. Various modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiments described in the present invention can better disclose the principle and practical application of the present invention, and enable those of ordinary skill in the art to understand the present invention.

The flow chart described in the present invention is only an embodiment, and there may be various modifications and changes to this illustration or the steps in the present invention without departing from the spirit of the present invention. For example, these steps can be performed in different orders, or certain steps can be added, deleted, or modified. Those of ordinary skill in the art may understand that all or part of the processes for implementing the above embodiments and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims (19)

1. An optical detection module, characterized in that the optical detection module includes:

   The photoelectric conversion circuit is used to convert the optical pulse signal reflected by the object into an electrical pulse signal;

   N digitizing modules, the N digitizing modules are connected in series or in parallel to the photoelectric conversion circuit for converting the electrical pulse signal into N digitizing signals, N ≥ 2; wherein, the nth digitizing module includes An nth stage amplifier circuit and an nth stage digitization circuit, the output end of the nth stage amplifier circuit is connected to the input end of the nth stage digitization circuit, n=1, 2, ...

   An arithmetic circuit is used to determine the distance between the object and the light detection device according to the n digitized signals.
2. The photodetection module according to claim 1, wherein when the N digitizing modules are connected in series to the photoelectric conversion circuit, the n+1th stage amplifying circuit is used for the nth stage The output signal of the amplifier circuit is amplified to obtain the n+1th stage amplified signal;

   The n+1th stage digital circuit is connected to the n+1th stage amplification circuit, and is configured to convert the n+1th stage amplification signal into an n+1th stage digital signal.
3. The light detection module of claim 1, wherein when the N digitizing modules are connected in parallel to the photoelectric conversion circuit, the magnifications of the N digitizing modules are different.
4. The light detection module according to any one of claims 1 to 3, wherein the n-th digitizing circuit includes a time-to-digital converter or an analog-to-digital converter.
5. The photodetection module according to claim 4, wherein when the n-th digitizing circuit includes an analog-to-digital converter, the analog-to-digital converter converts the n-th amplified signal based on a predetermined sampling frequency It is the n-th digitized signal.
6. The photodetection module according to claim 4, wherein when the n-th digitizing circuit includes a time-to-digital converter, the time-to-digital converter includes several different sampling thresholds; The number of sampling thresholds of the level digitizing circuit is greater than the number of sampling thresholds of the nth level digitizing circuit.
7. The light detection module according to claim 1, wherein the arithmetic circuit determines the weight of the N digitized signals according to a predetermined strategy, and obtains the received light based on the N digitized signals and the corresponding weights Pulse signal reception time.
8. The light detection module according to claim 7, wherein the predetermined strategy comprises: determining the weight of the n-th digitizing circuit according to the intensity of the received optical pulse signal.
9. The photodetection module of claim 1, wherein the n-th stage amplifier circuit includes an operational amplifier, a first resistor, and an amplifier bypass circuit; wherein, one end of the first resistor receives the electrical pulse Signal, the other end of the first resistor is connected to the inverting input of the operational amplifier, the positive input of the operational amplifier is connected to the reference voltage, and the output of the operational amplifier outputs the amplified electrical pulse signal; The amplifier bypass circuit is connected between the inverting input terminal and the output terminal of the operational amplifier.
10. The light detection module of claim 9, wherein the amplifier bypass circuit includes a second resistor; or a circuit in which the second resistor and the third resistor are connected in series.
11. The light detection module of claim 10, wherein the amplifier bypass circuit further includes a first diode; the first diode is connected in parallel with the second resistor or the third resistor.
12. The photodetection module of claim 9, wherein the n-th stage amplification circuit includes a current bypass circuit connected to one end of the first resistor for limiting the current passing through the first resistor .
13. The photodetection module of claim 12, wherein the current bypass circuit includes a second diode.
14. The photodetection module according to claim 9, wherein the nth-stage amplifier circuit includes a voltage bypass circuit connected to the output terminal of the operational amplifier, for limiting the nth-stage amplifier circuit. The output voltage.
15. The photodetection module according to claim 14, wherein the voltage bypass circuit includes a fourth resistor and a third diode, one end of the fourth resistor is connected to the output end of the operational amplifier, The other end of the fourth resistor is connected to the anode of the third diode and serves as the output of the n-th stage amplifier circuit, and the cathode of the third diode is grounded.
16. A distance measuring device, characterized in that it includes:

    Transmitting module, used to transmit optical pulse sequence;

    A scanning module, used to sequentially change the propagation path of the optical pulse sequence emitted by the transmitting module to different directions to exit;

    The light detection module according to any one of claims 1 to 15, wherein at least a part of the light signals reflected by the light pulse sequence through the object are incident on the photoelectric conversion circuit in the light detection device after passing through the scanning module, The photoelectric conversion circuit is used to convert the at least part of the optical signal into an electrical pulse signal.
17. The distance measuring device according to claim 16, wherein the scanning module includes a moving optical element for changing the propagation direction of the light pulse sequence from the distance measuring module before exiting.
18. The distance measuring device according to claim 10, wherein the optical element comprises a first light refracting element and a second light refracting element disposed oppositely, the first light refracting element and the second light refracting element Both include a pair of opposite non-parallel surfaces;

    The scanning module further includes a driving module for driving the first light refractive element and the second light refractive element to rotate at different speeds and/or directions.
19. The distance measuring device according to claim 11, wherein the optical element further comprises a third light refraction element arranged in parallel with the first light refraction element and the second light refraction element, the third The light refraction element includes a pair of non-parallel surfaces opposite to each other;

    The driving module is also used to drive the third light refracting element to rotate around a rotation axis.

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